The nature of the immunologic defect that predisposed certain patients to chronic and recurrent fungal infections such as mucocutaneous candidiasis has been further defined. Certain patients have abnormal ratios of T mu to T gamma lymphocytes that are compatible with a problem with regulation of immunocyte function. A new lymphokine, E-RAF, has been defined. It seems to induce maturation of "null" cells into E-rosette-forming T-cells. These observations indicate that "null" cells are not "null", but are pre-T-cells. Two therapies for chronic mucocutaneous candidiasis have been studied. A controlled clinical trial has shown that clotrimazole troches are effective therapy for chronic oral candidiasis. Transfer factor from candida-sensitive donors may restore the cellular immune responses to candida to these patients and prolong drug-induced remissions.